Field of the Invention
The present invention relates to an object information acquiring apparatus, an information processing apparatus and an object information acquiring method.
Description of the Related Art
Ultrasound imaging devices for imaging of three-dimensional structures in the interior of an object, using ultrasound waves, are widely used as ultrasound diagnosis devices in the medical field.
The performance of ultrasound diagnosis devices improves rapidly year by year in the wake of advances in ultrasound imaging technology. Image reconstruction relying on adaptive signal processing is being researched as one technology aimed at further enhancing that performance. For instance, J. F. Synnevag, et al., “Adaptive Beamforming Applied to Medical Ultrasound Imaging”, IEEE Trans. ULTRASONIC, FERROELECTRICS, AND FREQUENCY CONTROL, VOL. 54, NO. 8, AUGUST 2007, reports an ultrasound wave beamforming technology that relies on adaptive signal processing in the form of a DCMP (Directionally Constrained Minimization of Power) method.
The DCMP method is an adaptive signal processing technology developed as one technology in adaptive antennas. The DCMP method is a reception method that involves adaptively adjusting reception directionality on the basis of a constraint condition, namely rendering constant the reception gain of arriving waves in a desired direction, and minimizing the intensity of all reception signals including interfering waves. This method allows minimizing the ratio of interfering wave intensity with respect to signal intensity, and hence allows receiving signals having good SN ratio. As is likewise known, this method allows improving resolution and contrast in reconstructed images as compared with ordinary beamforming methods that are based on delay-and-sum. The DCMP method is also referred to as the CAPON method.
The specification of US Patent Application Publication No. 2003/0065262 (Patent Literature 2) and the specification of U.S. Pat. No. 6,798,380 (Patent Literature 3) disclose calculation methods in instances where the DCMP method is used in ultrasound imaging. Japanese Patent Application Laid-Open No. 2010-200926 (Patent Literature 1) discloses a beam signal synthesis method in which an output signal from beamforming based on the DCMP method and an output signal from delay-and-sum beamforming are compared, and the smaller signal is outputted.    Patent Literature 1: Japanese Patent Application Laid-Open No. 2010-200926    Patent Literature 2: Specification of US Patent Application Publication No. 2003/0065262    Patent Literature 3: Specification of U.S. Pat. No. 6,798,380    Non Patent Literature 1: J. F. Synnevag, et al., “Adaptive Beamforming Applied to Medical Ultrasound Imaging”, IEEE Trans. ULTRASONIC, FERROELECTRICS, AND FREQUENCY CONTROL, VOL. 54, NO. 8, AUGUST 2007